The present invention pertains to semiconductor quantum well electron and hole waveguides and a method for fabricating them and, in particular, to semiconductor quantum well electron and hole waveguides for ballistic electrons and holes.
Recent progress in semiconductor growth technologies, particularly in molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD), enable those of ordinary skill in the art to grow multilayered superlattice structures with precise monolayer compositional control. Further, refinements of these methods have produced improvements in the crystalline quality of materials such as GaAs so that devices have been observed in which ballistic electron transport exists, that is, devices where conduction electrons move through the material without being scattered. Still further, reported experiments have shown that ballistic hole motion also occurs in GaAs, albeit at a lower fraction than that which occurs for electron motion due to the peculiar structure of the valence band of GaAs.
In accordance with a paper entitled "Electron Wave Optics In Semiconductors" by T. K. Gaylord and K. F. Brennan, in J. Appl. Phys., Vol. 65, 1989, at p. 814 and a patent application entitled "Solid State Quantum Mechanical Electron and Hole Wave Devices," Ser. No. 07/272,175, which patent application was filed on Nov. 16, 1988, which patent application is commonly assigned with the present invention, and which patent application is incorporated by reference herein, ballistic electrons are quantum mechanical deBroglie waves which can be refracted, reflected, diffracted, and interferred in a manner which is analogous to the manner in which electromagnetic waves can be refracted, reflected, diffracted, and interferred. Further, phase effects for electron waves, such as path differences and wave interferences, may be described using a wavevector magnitude k given by: EQU k=[2m.sup.* (E-V)].sup.1/2 /n (1)
where m.sup.* is the electron effective mass, E is the total electron energy, V is the electron potential energy, and n is Planck's constant divided by 2.pi.. Still further, amplitude effects for electron waves, such as transmissivity and reflectivity, may be described in terms of an electron wave amplitude refractive index n.sub.e (amplitude) which is given by: EQU n.sub.e (amplitude).varies.[(E-V)/m.sup.* ].sup.1/2 ( 2)
Using eqn.'s (1) and (2), the characteristics of an unbiased, many boundary semiconductor lattice can be determined in accordance with the material disclosed in the above-cited patent application. In addition to this, however, there is a need in the art for electron and/or hole waveguide devices for use in fabricating analogs of integrated optical devices and the disclosure set forth in the above-cited publication and patent application does not address such electron and/or hole waveguide devices.